Handrails on escalators and moving walkways are moved by drive systems which typically are positioned along the return path of travel of the handrail, and which typically engage the handrail in some sort of nip through which the handrail passes. The drive system may include a plurality of friction rollers forming the drive nip; or drive belts; or a combination of belts and rollers. The drive system will typically include a powered component and a reaction or pressure component, both of which can be either a roll or a belt.
Some of the prior art handrail drive systems will create a constant nip pressure on the handrail; and others operate in such a manner as to create a variable nip pressure, which is proportional to the frictional drag imparted to the handrail by changes in the number of passengers on the conveyor, or the like.
Ideally, the handrail drive system should be capable of being adjusted so as to be able to produce a variety of nip pressures; and should provide enhanced contact with the handrail for increased driving power.
U.S. Pat. No. 3,414,109 Clark, granted Dec. 3, 1968; U.S. Pat. No. 3,666,075 Iwata, granted May 30, 1972; U.S. Pat. No. 4,134,883 Mendelsohn, et al., granted Jan. 16, 1979; U.S. Pat. No. 4,151,903 Takahashi, et al., granted May 1, 1979; and U.S. Pat. No. 4,200,177 Sato, et al., granted Apr. 29, 1980 are typical prior art disclosures of passenger conveyor handrail drives.